Shock-absorbing device for a ski or the like

ABSTRACT

A shock-absorbing device for a gliding board. The gliding board includes two laterally spaced apart transmission rods; at least one fixed connection making it possible to rigidly connect the first ends of both rods to the gliding board; and at least one casing adapted to be connected rigidly to the board at a certain distance from the fixed connection, which has an opening for the introduction of an inserted portion of each rod, and at least one housing containing a viscoelastic material which is in contact with the longitudinal sliding surface along at least a certain length of the insertable portion of each rod in the housing, the material being biased in shearing during the displacement of each rod portion in the housing. An object of the invention is to provide a device that absorbs both the flexional and torsional forces of the portions of a gliding board that are the most exposed to these phenomena.

BACKGROUND OF THE INVENTION

The invention relates to a shock-absorbing device for gliding boards,such as an alpine ski, a cross-country ski, a monoski, or a snowboard.It relates as well to a ski equipped with such a device.

DESCRIPTION OF BACKGROUND AND RELEVANT INFORMATION

While on the snow, the currently available skis are subjected to shocksor more or less extended bending stresses which cause the ski tovibrate. These vibrations are for the most part negative parasiticeffects which cause the loss of adherence between the ski and the snow,which adversely affects the steering and stability of the ski.

Various solutions have already been proposed in order to improve thevibrational behavior of a ski. The document FR-A-2 575 393 proposes toarrange a device of shorter length with regard to the supporting lengthof the ski and its positioning occurs in the zones that arepredetermined as a function of the types of vibration which it isdesirable to absorb.

Another more recently published solution in the document FR-A-2 675 392consists of taking up the flexion forces applied to the ski through oneflexion blade of which one end is fixed to the ski and the other end islinked to an interface made of a viscoelastic material which issubjected to the shearing of the blade. The interface can either beconnected directly above the ski, or can be attached to the innersurface of a stirrup or of a protection spoiler.

One of the main advantages of such a design is to obtain a satisfactoryshock-absorption of the vibrations by using a system whose height spacerequirement on the ski is reduced to a minimum. The shock-absorbingeffect is accompanied by a dynamic stiffening of the ski, a function ofthe length of the flexion blade and of the shear strength opposing thefree end of the ski. Conversely, the static rigidity of the ski is notaffected by the arrangement of such a system since no prestress isopposed to the free end by the shock-absorption means which operates inshearing.

However, the bending stresses are not the only stresses which appearwhen operating the ski.

When the ski is moving on the snow, it is subjected to three types offundamental stresses: the bending stresses, the torsional stresses andthe stresses of “lateral deformation.” In addition to these stresses,the vibrating phenomena occur at certain speeds as a function ofirregularities of the terrain, which in turn generates flexional andtorsional deformation of the ski in various ways.

The torsional stresses or vibrational phenomena of the ski appear eitherin raised regions, or more frequently in turns when the downhill skiimparts substantial pressure on the inner edge. It can also be observedthat the torsional stresses are maximum on the external zones of the skiand are for the most part oriented at a 45 degree angle with respect tothe longitudinal axis. Furthermore, the stresses vary along the ski andincrease in the direction of each of the ends, at the shovel and tail.Unusually larger skis, such as powder snow skis, are subjected to morestress at the ends; and there does not exist any device which permitsthe stresses to be absorbed in an efficient manner.

None of the prior art devices provide a satisfactory solution fordiminishing the various stresses and vibratory phenomena.

SUMMARY OF THE INVENTION

The object of the present invention is thus to propose a device whichabsorbs both flexional deformation and torsional deformation of theportions of the gliding board that are most exposed to these phenomena.

To this end, the invention concerns a shock-absorbing device for agliding board. The device includes:

two transmission rods laterally spaced apart,

at least one fixed connection making it possible to rigidly connect thefirst ends of both rods to the gliding board,

at least one casing adapted to be connected rigidly to the board at acertain distance from the fixed connection, which has an opening for theintroduction of a retractable portion of each rod, and a housingcontaining a viscoelastic material which is in contact with thelongitudinal sliding surface along a certain length, at least, of theretractable portion of each rod; said material being biased in shearingduring the displacement of each rod portion in the housing.

According to another characteristic of the invention, the two rods areoriented with respect to each other in a substantially parallel manner.

The invention equally relates to a ski, particularly of the alpine type,including the shock-absorbing device. The transmission rods are orientedsubstantially in the longitudinal direction, each being offset on eitherside of the vertical median plan P. The more the rods are laterallyoffset in relation to this plane, the more the torsional shock-absorbingeffect proves efficient.

Thus, the device is particularly sensitive to flexional deformations ofthe elongated beam which constitutes the ski, as well as to torsionaldeformations thereof. The device is also particularly adapted to powdersnow skis, whose front and rear widths are greater than normal.

According to a complementary characteristic, the ski includes a firstdevice located between the shovel zone and the mounting zone of thebindings, and a second device located between the mounting zone of thebindings and the tail zone.

It is in these areas, in effect, that the bending is maximum, whereas itis necessary to improve the contact between the ski and the snow.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will becomeapparent from the description which follows, with reference to theannexed drawings which are only provided by way of non-limitingexamples, and in which:

FIG. 1 is a top view of a ski on which two devices are mounted accordingto the invention.

FIG. 2 is an enlarged view of a detail of FIG. 1.

FIG. 3 is a cross-section along III—III of FIG. 1.

FIG. 4 is a cross-section along IV—IV of FIG. 1.

FIG. 5 is a cross-section along V—V of FIG. 1.

FIG. 6 is a cross-section along VI—VI of FIG. 3.

FIG. 7 is a cross-section along VII—VII of FIG. 5.

FIGS. 8 and 9 are schematic views of the working principle of the deviceduring torsion.

FIG. 10 is a schematic view of the working principle of the deviceduring flexion.

FIG. 11 is a cross-sectional view similar to the view of FIG. 3according to an alternative embodiment.

FIG. 12 is a cross-sectional view similar to the view of FIG. 3according to another alternative embodiment.

FIG. 13 is a top view of the front of the ski according to thealternative embodiment of FIG. 12.

FIG. 14 is a view similar to that of FIG. 13 according to anotheralternative embodiment.

FIG. 15 is a view similar to that of FIG. 4 according to anotheralternative embodiment.

FIG. 16 is a view similar to that of FIG. 1 according to anotheralternative embodiment.

FIG. 17 is a partial schematic cross-section along XVII—XVII of FIG. 16.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a ski 1, in particular an alpine ski, constituted by anelongated beam having its own distribution of thickness, of width and,therefore, its own stiffness. It includes a central portion or mountingzone 10 adapted for the mounting of the binding elements (dotted lines),a shovel zone 11 located at the front of the ski, a tail zone 12 locatedin the rear of the ski.

A first device 2 according to the invention is located on the uppersurface of the ski between the mounting zone 10 and the shovel zone 11.Likewise, a second device 3 is located on the upper surface between saidzone 10 and the tail zone 12. This arrangement allows forshock-absorption at the front and rear portions of the ski which are themost biased during flexional and torsional deformation.

The following detailed description of the device 2 of the front of theski therefore applies to in the same manner to device 3 in the rear ofthe ski. The shock-absorption device 2 includes two transmission rods20, 21 substantially parallel to one another and located on both sidesof the median vertical plane P. These rods are laterally spaced from oneanother, i.e., in a direction perpendicular to the longitudinaldirection set out by the median vertical plane P. Each rod 20, 21includes a first end 20 a, 21 a connected to a fixed connection 22 whichfirmly holds these ends on the ski without any possibility of movement.

The second ends 20 b, 21 b of the rods are connected to the ski by aflexible connection which includes a casing 23 rigidly connected to theski. Between the connection 22 and the casing 23, along the distance Dshown, the rods are perfectly free and have no connection with the ski.One can however tolerate the addition of a means for guidinglongitudinal displacements, for example, to avoid a possible problem ofbuckling of the rods, which can occur during an exceptional flexionaldeformation (not shown).

As shown in FIG. 2, the casing 23 includes openings 231 a, 231 b toenable introduction of the respective second ends 20 b, 21 b of the rodsinto the casing. These openings must be sufficient for allowing a freetranslational and rotational sliding.

A recess 230 whose volume must also be sufficient, particularly indepth, is provided within the casing to enable a free translationaldisplacement of each rod. It is particularly important, in effect, thatthe free end 20 b, 21 b of each rod not be capable of coming intoabutment against the end 230 a of the housing in the casing in order toavoid any stiffness of the ski starting from a certain point (FIG. 7).

The volume of the recess 230 is particularly filled with ashock-absorbing block 25 of viscoelastic material. The material isselected, advantageously, from the family of mineral or organic resins.In this case, the material is sufficiently adhesive to adhere to theelements with which it comes into contact in order to sustainsubstantial shearing during the translational or rotational displacementof ends 21 a, 21 b in the recess of the casing.

The shock-absorbing block 25 enters into contact with the tubularsliding surface along a certain length l of the retractable portion orend 20 b, 21 b of each rod i.e., the portion that is inserted orpositioned within the recess 230 of the housing 23.

The fixed connection 22 is in the form of a second casing adapted to beconnected to the ski by any means, such as adhesion, welding, orscrewing, and into which the first ends 20 a, 21 a of the rods 20, 21penetrate. These ends 20 a, 21 a are connected rigidly to the casing 22by means of an adhesive layer 220, for example (FIG. 6).

Each rod 20, 21 is preferably made of a high modulus material with abasis of glass, carbon, acrylic or polyester fibers, or of a mixture ofsaid fibers.

The plastic material which contains these fibers may be a thermosettingresin, preferably of the epoxy type, or a thermoplastic resin.

The advantage of utilizing a composite material rather than metal isderived from the low thermal expansion of the composite with respect tothe metal and its lightness.

On the other hand, one of the disadvantages of the composite is its lowcrushing and impact strength. It is therefore necessary to protect eachrod with an external sheath 4 made of a flexible plastic material. Thesheath must extend along the distance D between the fixed connection 22and the casing 23. Preferably, such a sheath is made of polyamide,polyurethane, or extruded ionomer.

However, one can also envision the utilization of metallic rods made ofstainless steel, aluminum or the like, in particular for intensive useof the device during competition.

For economical reasons, the rods and their sheath have a constantsection along the entire length.

Tests have been performed on rods constituted by a hollow tube that hasone or more inner glass fiber layers and covered by one or more outercarbon layers. The glass provides a proper crushing strength. Withrespect to carbon, its usage is justified by its high modulus whichenables the external diameters of the tube to remain relatively small;this advantageously limits the space requirement of the device. Ofcourse, the risks of crushing can also be limited by utilizing solidtubes, as shown in the various figures.

Thus, in a general manner, the external diameter of the tubes iscomprised between 4 and 8 mm, preferably between 5 and 6 mm.

FIGS. 8 and 9 illustrate the working principle of the device on a skiwhen a purely torsional deformation occurs in the area covered by thedevice.

In the resting state shown in FIG. 8, no displacement is recorded. Whena torque C is applied, an angular displacement of each free rod end 20b, 21 b is recorded. This rotation is accompanied by the relative comingof the ends closer to the vertical longitudinal plane P, thereforenecessarily by a short longitudinal retreat in the housing in thecasing. When the torque is released, the ends 21 a, 21 b return to theirinitial position.

These to-and-fro rotational and translational displacements generateshearing forces, and therefore energy dissipation, in theshock-absorbing block.

FIG. 10 illustrates the working principle of the device during pureflexion. When a shearing force F is applied to the area of the device inthe direction indicated, for example, during a violent impact betweenthe front of the ski shown and the ground, a relative displacement ofeach free end 20 b, 21 b of the rods in the direction of the casing 23(along the direction of the arrow d) is noted. This displacement is thusbraked by the shock-absorbing block 25. Of course, braking and thereforeshock-absorption also occur in the opposite relative displacements, i.e.along a direction opposite d, during return movements to the initialposition and along a reversed arrow, i.e., along a direction opposite F.

Of course, it is to be understood that the displacements generated are afunction of the length of the rods and their shift with respect to theneutral fiber of the ski, and also of the lateral shift of the rods withrespect to the vertical median plane P of the ski.

FIG. 11 shows a variation of the invention in which the casing 23includes two separate recesses 230 b, 230 c each receiving the end 20 b,21 b of the rods. Each housing is fitted with a distinct shock-absorbingblock 25 a, 25 b. This embodiment, with respect to the previous one, hasthe advantage of having a constituent material of the block 25 a whichhas different characteristics with respect to the material of the block25 b (hardness, resiliency, viscosity, tangent, etc.). One can thusadapt the shock-absorption on the side of the inner running edge of theski, where the supports are stronger, in a differential and specificmanner with respect to the side of the outer running edge of the skiwhere the supports are weaker.

FIG. 12 shows another variation where the device includes two distinctcasings 23 a, 23 b each provided with a distinct recess.

The rods 20, 21 are not necessarily parallel, but can be divergenttoward the ends of the ski, on the front portion of the ski, as shown byway of example in FIG. 13. As in the preceding embodiment, the devicecan advantageously include two distinct casings 23 a, 23 b laterallyspaced apart along the width of the front of the ski, as well as twodistinct and separate fixed connections 22.

The rods do not necessarily have the same length but can, on the otherhand, have a different length as needed, as shown in FIG. 14, so as todifferentially affect the supports on the inner side and outer side ofthe ski.

The rods 20, 21 can have a non-circular shape, such as a flattened,substantially hemicircular shape shown in FIG. 15. Such a shapecontributes to lower the neutral fiber of the section of the rod so thatit resists better to buckling during bending.

Another alternative embodiment shown in FIGS. 16 and 17 calls for threecasings and threes rods.

This alternative embodiment is shown in a top view in FIG. 16. The ski 1includes a device 3, a mounting zone 10, a shovel zone 11 and a tail 12,as has already been described. A device 40 is located between themounting zone 10 and the shovel zone 11. The device 40 includes a frontcasing 41, a central casing 42, and a rear casing 43. A rod 44 connectsthe front casing 41 to the central casing 42, and two rods 45, 46connect the central casing 42 to the rear casing 43.

The device 40 functions in the following manner, explained by means ofFIG. 17.

The rod 44 is affixed through one end to the casing 41 in a fixedmanner, for example, by adhesion or screwing in an opening of the casing41. The other end of the rod 44 is guided in an open cavity of thecentral casing 42 by a shock-absorbing block 47 arranged between the rod44 and walls of the cavity. Of course, a space 48 of the cavity enablesa displacement of the rod 44 in the cavity without the end of the rod 44touching the bottom of the cavity when the ski 1 becomes deformed.

Similarly, the rods 45, 46 each have one end fixedly connected to therear casing 43, and one end that is movable with respect to the casing42.

The cross section of FIG. 17 shows one end of the rod 45 affixed in anopening of the casing 43, and the other end of the rod 45 is capable ofbeing displaced in a cavity of the casing 42 by friction on a shockabsorbing block 49. Of course, a recess 50 of the cavity of the casing42 prevents the end of the rod 45 from touching the bottom of the cavitywhen the ski 1 becomes deformed.

The rod 46, not visible in FIG. 17, is connected through its ends to thecasings 42 and 43 in a manner similar to the connection of the rod 45 tothe same casings 42 and 43.

One can provide to vary the intensity of the shock-absorption of therods 44, 45, and 46 on their respective shock-absorbing blocks, forexample by changing the type of material constituting theshock-absorbing blocks, or by modifying their compression state betweenthe rod and the walls of the cavity, for example by adjusting thedimensions of the parts of the device 40.

This alternative embodiment of the invention makes it possible to manageflexional and torsional deformations in selected areas of the ski 1. Inparticular, the rod 44 more specifically controls flexionaldeformations, whereas the rods 45 and 46 control both flexional andtorsional deformations.

The invention is not limited to the embodiments which have beenexpressly described, but it includes the various variations andgeneralization thereof contained in the claims that follow.

What is claimed is:
 1. A shock-absorbing device for a gliding board,said device comprising: two transmission rods laterally spaced apart,each of said transmission rods having a first end portion and a secondend portion, said first end portions constituting fixed end portions andsaid second end portions constituting movable end portions; at least onefixed connection adapted to connect said first end portions of said twotransmission rods rigidly to the gliding board; at least one casingadapted to be connected rigidly to the gliding board at a certaindistance longitudinally spaced from said fixed connection, said at leastone casing having openings through which said second end portions areintroduced, each said opening having a size sufficient to permit freetranslational and rotational sliding of said second end portions, saidat least one casing further having at least one recess for housing saidsecond end portions of said two transmission rods, each of said recessescontaining a viscoelastic material; each of said second portions of saidtransmission rods having a longitudinally extending sliding surfacealong a certain length and in contact with said viscoelastic material,said second portions of said transmission rods being arranged forrotational and translational movement in said at least one recess andbeing biased in shearing with said viscoelastic material during saidmovement wherein: said two transmission rods are offset relative to oneanother and operate independently of one another.
 2. A shock-absorbingdevice according to claim 1, wherein: said two transmission rods areoriented substantially parallel to one another.
 3. A shock-absorbingdevice according to claim 1, wherein: said at least one casing comprisesonly a single casing into which said second end portions of saidtransmission rods extend.
 4. A shock-absorbing device according to claim1, wherein: said at least one fixed connection comprises a second casingadapted to be connected to the ski by an adhesive, a weld, or screws,and into which said first end portions of said two transmission rodsextend.
 5. A shock-absorbing device according to claim 1, wherein: eachof said transmission rods is made of a high modulus material made ofmetal or having a basis of glass, carbon, acrylic or polyester fibers,or of a mixture of such fibers.
 6. A shock-absorbing device according toclaim 4, wherein said first end portions of said two transmission rodsare rigidly connected to said second casing by means of an adhesivelayer.
 7. A shock-absorbing device according to claim 5, wherein:between said fixed connection and said casing, each of said transmissionrods is protected with an external sheath made of a flexible plasticmaterial.
 8. A shock-absorbing device according to claim 5, wherein:each of said transmission rods is constituted by a hollow tube havingone or more inner glass fiber layers and covered by one or more outercarbon layers.
 9. A shock-absorbing device according to claim 7,wherein: each of said sheaths is made of polyamide, polyurethane, orextruded ionomer.
 10. A shock-absorbing device according to claim 8,wherein: each of said hollow tubes has an outer diameter of between 4and 8 mm.
 11. A shock-absorbing device according to claim 8, wherein:each of said hollow tubes has an outer diameter of between 5 and 6 mm.12. A shock-absorbing device for a gliding board, said devicecomprising: means for absorbing flexional and torsional forces imposedon the gliding board, said means comprises: two transmission rodslaterally spaced apart, each of said transmission rods having a firstend portion and a second end portion, said first end portionsconstituting fixed end portions and said second end portionsconstituting movable end portions; at least one fixed connection adaptedto connect said first end portions of said two rods rigidly to thegliding board; at least one casing adapted to be connected rigidly tothe gliding board at a certain distance longitudinally spaced from saidfixed connection, said at least one casing having openings through whichsaid second end portions are introduced, said at least one casingfurther having at least one recess for housing said second end portionsof said two transmission rods, each of said recesses containing aviscoelastic material; each of said second portions of said transmissionrods having a longitudinally extending sliding surface along a certainlength and in contact with said viscoelastic material, said secondportions of said transmission rods being arranged for rotational andtranslational movement in said at least one recess and being biased inshearing with said viscoelastic material during said movement.
 13. Incombination, a ski and a shock-absorbing device, said shock-absorbingdevice comprising: two transmission rods laterally spaced apart, each ofsaid transmission rods having a first end portion and a second endportion, said first end portions constituting fixed end portions andsaid second end portions constituting movable end portions; at least onefixed connection connecting said first end portions of said two rodsrigidly to said ski; at least one casing connected rigidly to said skiat a certain distance longitudinally spaced from said fixed connection,said at least one casing having openings through which said second endportions are introduced, said at least one casing further having atleast one recess for housing said second end portions of said twotransmission rods, each of said recesses containing a viscoelasticmaterial; each of said second portions of said transmission rods havinga longitudinally extending sliding surface along a certain length and incontact with said viscoelastic material, said second portions of saidtransmission rods being arranged for rotational and translationalmovement in said at least one recess and being biased in shearing withsaid viscoelastic material during said movement.
 14. The combinationaccording to claim 13, wherein: said ski is an alpine ski.
 15. Thecombination according to claim 13, wherein: said ski has a verticalmedian plane and said transmission rods are oriented substantiallylongitudinally, each being offset on either side of the vertical medianplane.
 16. The combination according to claim 13, wherein: said skiincludes a shovel zone, a tail zone, and a binding mounting zone betweensaid shovel zone and said tail zone; said device is located between saidshovel zone and said binding mounting zone; said combination furthercomprising a second shock-absorbing device located between said bindingmounting zone and said tail zone.
 17. The combination according to claim13, wherein: said two transmission rods are oriented substantiallyparallel to one another.
 18. The combination according to claim 13,wherein: said at least one casing comprises only a single casing intowhich said second end portions of said transmission rods extend.
 19. Thecombination according to claim 13, wherein: said at least one fixedconnection comprises a second casing adapted to be connected to the skiby an adhesive, a weld, or screws, and into which said first endportions of said two transmission rods extend.
 20. The combinationaccording to claim 13, wherein: each of said transmission rods is madeof a high modulus material made of metal or having a basis of glass,carbon, acrylic or polyester fibers, or of a mixture of such fibers. 21.The combination according to claim 19, wherein: said first end portionsof said two transmission rods are rigidly connected to said secondcasing by means of an adhesive layer.
 22. The combination according toclaim 20, wherein: between said fixed connection and said casing, eachof said transmission rods is protected with an external sheath made of aflexible plastic material.
 23. The combination according to claim 20,wherein: each of said transmission rods is constituted by a hollow tubehaving one or more inner glass fiber layers and covered by one or moreouter carbon layers.
 24. The combination according to claim 22, wherein:each of said sheaths is made of polyamide, polyurethane, or extrudedionomer.
 25. The combination according to claim 23, wherein: each ofsaid hollow tubes has an outer diameter of between 4 and 8 mm.
 26. Thecombination according to claim 23, wherein: each of said hollow tubeshas an outer diameter of between 5 and 6 mm.